<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta name="Anthor" content="月影-253737688" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
    <title>一个div如何被三个内部div划分出四个等间距？用纯css,html</title>
    <style>
        *{margin: 0; padding: 0}
        .wrapper{
            display: flex;
            flex-wrap: wrap;
            width: 900px;
            border:1px solid black;
            margin: 0 auto;
        }
        .item{
            width: 25%;
            height: 200px;
            border:1px solid red;
            margin-left: calc((900px - 3*25%)/4);
        /*( 总宽度 减去 子节点个数 乘以 子节点宽度 ) 平均分配到（子节点个数+1）个区域*/
            margin-bottom:10px;
        }
    </style>
</head>
<body>
<p>一个div如何被三个内部div划分出四个等间距？用纯css</p>
<div class="wrapper">
    <div class="item"> </div>
    <div class="item"> </div>
    <div class="item"> </div>
    <div class="item"> </div>
    <div class="item"> </div>
</div>

<!--

https://segmentfault.com/q/1010000011073700/a-1020000011076544
https://segmentfault.com/q/1010000011244071/a-1020000011244170
-->
</body>
</html>